generic/398: Accept failing with EPERM in addition to ENOKEY for rename without key

generic/398: Accept failing with EPERM in addition to ENOKEY for rename without key

Some filesystems (e.g. UBIFS) fail with EPERM when trying to move a
file into an encrypted directory via cross rename, without having
access to the encryption key.

Since rename is perfectly allowed to return EPERM, which is also
tested for, and no precise specification seems to exist that
clarifies when to expect EPERM and when ENOKEY, this patch modifies
the generic/398 test to accept both, for the test case where the key
is not available.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>